Ben Richardson creates a visual:
Ever wished you could see exactly how customers move through your sales funnel, or how costs flow across your business?
A Sankey Diagram makes those flows visible, showing not just totals but how values split and connect between categories.
In Power BI, the Sankey Diagram is available as a custom visual from AppSource, designed to reveal relationships and flow patterns.
There are specific times and places for Sankey charts. It requires having a natural flow in your data—that is, you need different states of data, those states should typically only “move” in one direction, you have paths to get from one state to another, and there is enough variety in pathing that not all of the data is going to the same location. The more of these rules you violate, the less useful a Sankey diagram is.